This invention relates in general to light weight vehicle wheels and in particular to a light weight wheel assembly which includes a stylized wheel disc mounted upon a universal one piece cast wheel and a process for manufacturing the wheel assembly.
Cast vehicle wheels formed from alloys of light metals, such as aluminum, magnesium and titanium have become increasingly popular. Such cast wheels provide both a reduction in weight from steel wheels and can be cast having an attractive stylized appearance.
Referring now to the drawings, there is illustrated in FIG. 1 a perspective view of a typical one piece cast vehicle wheel, shown generally at 10, which is formed in accordance with the prior art. The wheel 10 includes an annular wheel rim 11 which is adapted to carry a pneumatic tire (not shown). The rim 10 has an inboard end 12 which is adjacent to a vehicle (not shown) when the wheel 10 is mounted thereon and an outboard end 13 which is opposite from the inboard end 12. The wheel 10 further includes a circular wheel disc 15 which extends radially across the outboard end 13 of the wheel rim 11. The wheel disc 15 includes an annular sidewall 17 formed on the outboard end of the wheel rim 11. A plurality of radially extending wheel spokes 18 support a central wheel hub 20 within the sidewall 17. The hub 20 includes a recessed center portion 21 having a central pilot hole 22 formed therethrough. The center portion also has a plurality of apertures 23 formed therethrough. The apertures 23 are spaced equally about a bolt circle which is concentric with the pilot hole 22. When the wheel 10 is mounted upon a vehicle, each of the apertures 23 receives a threaded wheel lug (not shown) for securing the wheel 10 upon the vehicle.
Components of molds used to cast such one piece wheels typically include a mold cavity having tapered surfaces to facilitate release of the wheel casting. The tapered surfaces cause the sidewall 17 to be relatively thick. Additionally, the mold structure usually requires the rim portion of the mold cavity to have a wide spacing in the radial direction. This allows molten metal to flow from risers located at the inboard end of the wheel mold cavity through the rim portion of the cavity to fill voids formed as the molten metal forming the casting sidewall 17 contracts during solidification. The wide rim cavity results in a relatively thick wheel rim.
It is known to decorate the outboard face of the wheel disc 15 by polishing the surface to a high luster and then sealing the surface with a layer of clear coat. Alternately, the wheel disc face can be painted or plated with a metal, such as chromium. Chrome plating typically requires sequential immersion of the wheel in a series of chemical baths while multiple layers of metal are electro-deposited onto the surface of the wheel. Because of the complexity of the plating process, it also is known to apply a decorative chrome plated overlay to the face of the wheel disc, as disclosed in U.S. Pat. No. 5,597,213 to Chase. Such overlays are typically vacuum formed from a plastic.